First off, which stats do you have? You must have damage and HP. If its a tabletop game, you must have move as well. Many games break 'Attack' into %Hit and Damage#. After which, you've typically got precedence (who hits first). Speed/# of attacks another one. Armor, either as damage reduction or a miss% is common. If you don't want to hate yourself, units will also have a 'cost' stat that can be used to balance all the others.

The more you 'chain' attributes together, the bigger the headache to balance. If your attack algorithm is: Priority, roll attack, roll damage, roll armor reduction, compare to HP, then you get to hate life, because each and every one is contingent on the outcome of the last, making balancing a misery.

Tracking HP for many units is kind of a pain, so the use of 'morale' seems a common wargame trope. So: Attack, Defense, Move, Morale, Cost. But attacks need ranges. MERCS minis did it well--units had 2+ weapons, each with their own range/damage. They also did HP well--units were either 'blooded' or dead.

I think you're approaching it from the wrong angle. The value of an asset in a wargame is the additional ability it gives you to win the game. You win the game by achieving your objectives (which might well be asymmetrical); and the setup might mean the right ways to look at balance are also asymmetrical. Take, for instance, one of the major issues of 20th-century strategy: Given that the United States has 10 battleships, how many battleships does Japan need to be able ensure victory over the United States? According to the Japanese high command the answer was 8. So the starting point for any analysis is "how does this unit help player win", not "what arbitrary statistics have I given this unit". Commonly, games seem to stumble on treating statistics as additive for balance purposes, or simply having "missed" statistics which don't vary when they ought to.

Very interesting. I had not considered the topic of asymmetrical wargames. Also, could you say more about missing statistics?

Health is a common one - particularly in situations where every unit has the same Health.

To take Axis and Allies, an Infantry has Attack 1, Defence 2, Cost 3 (=Attack+Defence) while an Armour has Attack 3 and Defence 2 and Cost 5 (=Attack+Defence). So on the whole you would expect 2 Infantry to have a slight advantage over 1 Armour, right, as the Infantry costs most? Wrong! The chances of 2 Infantry beating 1 Armour when the infantry are attacking are 2.8:1 and when the armour is attacking, they're 6:1. This is because when the dice turn up "both sides hit", each side loses one unit, and because there's only one tank, the Infantry win. The armour also has an additional point of Move, which looks like it ought to be an advantage, but actually is pretty trivial with the way the game plays.